The field of the invention pertains to collapsible plastic bottles and in particular to collapsible plastic bottles for foods and beverages, such as soda pop. Such bottles are constructed of plastics approved by the Food and Drug Administration for intimate and prolonged contact with foods and beverages. These bottles are commonly used for a variety of brands of soda pop and are formed of a clear plastic in a two-stage molding process. Typically, the two-stage molding process comprises an injection molded preform that is subsequently positioned in a bottle mold and blown to the full size of the bottle. In so doing, the side wall of the preform as the bottle is blown is stretched and tensioned to create an exceptionally sturdy thin-walled plastic bottle. Because the end of the preform, which eventually forms the bottom of the bottle, is not stretched axially as is the side wall, the bottom of the bottle does not possess the same strength as the side wall. Therefore, a separate plastic cup is fitted and affixed to the bottom of the bottle in a subsequent operation to reinforce the bottom of the bottle and prevent cracking or leakage in the handling of the filled bottle.